The present invention relates to a system for reproducing a stationary picture, such as a system for recording information from a motion picture on a recording medium as a still picture and reproducing the information from the recording medium.
In order to reproduce the information of the motion picture as a stationary picture, a system, for example, shown in FIG. 6 is used. In the motion picture, the feeding speed of the picture frames is twenty-four frames per second. On the other hand, the number of frames of the video disk is thirty frames per second. Accordingly, for example, the frames A, C, E, of the motion picture correspond to fields (A1, A2), (C2, C1), (E1, E2) of the video signal, respectively. The frames B, D correspond to the fields (B1, B2, B1), (D1, D2, D1) of the video signal, respectively. Namely, in the conventional video disk (LD), two or three adjacent fields in picture number are used as one frame to obtain a still picture of the frame. Here, letters A to E represent frames of respective pictures, and suffixes 1 and 2 represent field numbers of the video. Further, the picture number, as addresses representing each frame, is set at the head of each of the fields A1, B1, C2, D2, E1. Namely, the picture number is positioned regardless of the position of the frame as a unit of the video signal.
Operation of the conventional system will be described with reference to a block diagram of FIG. 7 and a timing chart of FIG. 8.
As shown in FIG. 7, a reproduced RF signal is demodulated into a video signal in an FM demodulator 1. The video signal is applied to a frame memory 2 for obtaining a still picture and further to a picture number detector 3 for detecting a picture number a and a field signal detector 4 for detecting a field signal b. The detected signals a and b are applied to a memory controller 5 which is applied with a still instruction c. The still instruction c becomes a high level when a still picture is required. The controller 5 produces a memory write enable signal d which is applied to the frame memory 2 controlling the writing operation.
As shown in FIG. 8, when the still instruction c is applied, the write enable signal d becomes a low level at the end of the second field from the picture number immediately after the still instruction c, thereby inhibiting the writing in the frame memory 2. Thus, the memory 2 produces an image in the frame (video signals D1, D2).
However, in the conventional system, since the picture number is positioned at the head of the field regardless of the frame, it is not determined which of the fields of the video signal is designated by the picture number. Therefore, it is difficult to read an address signal in a random access operation. Since the address signal does not correspond to each of the frames, the picture does not coincide with the actual time. In particular, if the film source is mixed with a video source, the operation can not be controlled.